1. Field of the Invention
The present invention relates to a method for manufacturing a substrate provided with a semiconductor layer with an insulating film interposed therebetween, particularly, a silicon-on-insulator (SOI) substrate.
2. Description of the Related Art
In recent years, integrated circuits which use a silicon-on-insulator (SOI) substrate in which a thin single crystal semiconductor layer is provided over an insulating surface, instead of a bulk silicon wafer, have developed. By utilizing characteristics of a thin single crystal silicon film formed over an insulating film, transistors formed in the integrated circuit can be separated from each other completely. Further, since fully-depleted transistors can be formed, a semiconductor integrated circuit with high added value such as high integration, high speed driving, and low power consumption can be realized.
One of known methods for manufacturing an SOI substrate is a Smart Cut (registered trademark) method. By using a Smart Cut method, an SOI substrate having a single crystal silicon film over an insulating substrate such as a glass substrate can be manufactured in addition to an SOI substrate having a single crystal silicon film over a silicon substrate (for example, see Patent Document 1). The method for manufacturing an SOI substrate having a single crystal silicon thin film over a glass substrate by a Smart Cut method is briefly described below. First, a silicon dioxide film is formed over a surface of a piece of single crystal silicon. Next, hydrogen ions are implanted into the piece of single crystal silicon to form a hydrogen ion implanted plane at a predetermined depth from a surface of the piece of single crystal silicon. Then, the piece of single crystal silicon into which the hydrogen ions are implanted is attached to a glass substrate with the silicon dioxide film interposed therebetween. After that, the hydrogen ion implanted plane becomes a cleavage plane by performing heat treatment, and the piece of single crystal silicon into which the hydrogen ions are implanted is separated into a thin film state, so that a single crystal silicon thin film can be formed over the attached glass substrate. Such a Smart Cut method may also be referred to as a hydrogen ion implantation separation method.